use std::collections::HashMap;↵
↵
type Kilometers = i32;↵
type UserId = u64;↵
type UserMap = HashMap<UserId, String>;↵
↵
fn distance_in_km(d: Kilometers) -> String {↵
format!("{} km", d)↵
}↵
↵
fn get_user(users: &UserMap, id: UserId) -> Option<&String> {↵
users.get(&id)↵
}↵
↵
fn main() {↵
let dist: Kilometers = 100;↵
println!("{}", distance_in_km(dist));↵
↵
let mut users: UserMap = HashMap::new();↵
users.insert(1, String::from("Alice"));↵
users.insert(2, String::from("Bob"));↵
↵
if let Some(name) = get_user(&users, 1) {↵
println!("User 1: {}", name);↵
}↵
}